1. Field of the Invention
The present invention relates generally to broadband data communications networks, and more particularly to a computer-based method for allocating bandwidth among several network termination nodes within such networks.
2. Related Art
Metropolitan area networks (MANs) are broadband networks that interconnect several local area networks (LANs) and are operated by network service providers (e.g., local exchange carriers (LECs)). Each of the interconnected LANs may cross administrative boundaries (i.e., be owned and operated by different customers or subscribers of the network service provider which comprise different “offices”).
A MAN is characterized by a Line Termination (LT) unit which is the “network-side” interface, operated by the network service provider, to each of the customers' Network Termination (NT) units. The LT represents the part of the broadband network where the network service provider's responsibility begins (for downstream data) and ends (for upstream data). In contrast, an NT unit is the “user-side” of the broadband network. Each NT is located at the customer premises and serves its LAN, Private Branch Exchange (PBX) and other local communications networks.
Within a MAN, the LT operated by the network service provider is responsible for aggregating all traffic from each of the NT units connected to it. This aggregation serves to connect customers' local voice data to the Public Switched Telephone Network (PSTN), and to connect other local data to various outside networks, such as Internet Protocol (IP) networks, Asynchronous Transfer Mode (ATM) networks and the like.
Within MANs, there are several technologies that are currently employed to transmit broadband (i.e., voice and other) data between the LT unit and the NT units. These technologies are often referred to as “Access” technologies and include Passive Optical Networks (PON), Wireless Local Loop (WLL) and Cable Modems. These different Access technologies, however, have one thing in common—a point to multi-point topology. That is, the MAN topology is a point (i.e., a single LT) to multi-point (i.e., multiple NTs) topology.
A point to multi-point topology creates a situation where the data flow within the MAN network is non-symmetrical. In the “downstream” direction (i.e., from the single LT to the multiple NTs), data is broadcast (i.e., simultaneously transmitted to all NTs) from the LT. In the “upstream” direction (i.e., from the multiple NTs to the single LT), however, a Time Division Multiple Access (TDMA) scheme is often employed. TDMA allows each NT to obtain a grant of a window (i.e., a “time slot”) when it can send voice and other data to the LT for eventual transmission to the PSTN, Internet and other wide area networks. Currently, there exists no general methodology that ensures an LT efficiently and fairly allocates system resources (e.g., bandwidth) while attempting to maintain the subscribed Quality of Service (QoS) among the several NTs within a MAN.
In view of the foregoing, a method of providing upstream QoS and bandwidth allocation within an LT unit in a point to multi-point broadband network is needed.